For typical bottom-emitting OLED display, transparent pixel electrodes are generally made from metal oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), etc. The transparent pixel electrodes can allow light to pass through the pixel electrodes and a substrate, to realize display and luminescence function. However, since a metal oxide film has a higher resistivity and can generate great heat, in order to obtain a lower resistance, an ITO film is generally needed to be deposited to reach a larger thickness, for example, the thickness is within a range from 200 nm to 300 nm. The thicker ITO film will result in the increase of manufacturing cost and, more importantly, potential low reliability. In particular, for a flexible display device, the pixel electrode having a larger thickness may tend to be broken or peeled off when the flexible display device is repeatedly bent, particularly for the ITO film with poor ductility. Therefore, what is needed is to provide a new type of electrode structure to solve the problem.